Lower serum hepcidin and greater parenchymal iron in nonalcoholic fatty liver disease patients with C282Y HFE mutations

Abstract

Hepcidin regulation is linked to both iron and inflammatory signals and may influence iron loading in nonalcoholic steatohepatitis (NASH). The aim of this study was to examine the relationships among HFE genotype, serum hepcidin level, hepatic iron deposition, and histology in nonalcoholic fatty liver disease (NAFLD). Single-nucleotide polymorphism genotyping for C282Y (rs1800562) and H63D (rs1799945) HFE mutations was performed in 786 adult subjects in the NASH Clinical Research Network (CRN). Clinical, histologic, and laboratory data were compared using nonparametric statistics and multivariate logistic regression. NAFLD patients with C282Y, but not H63D mutations, had lower median serum hepcidin levels (57 versus 65 ng/mL; P = 0.01) and higher mean hepatocellular (HC) iron grades (0.59 versus 0.28; P < 0.001), compared to wild-type (WT) subjects. Subjects with hepatic iron deposition had higher serum hepcidin levels than subjects without iron for all HFE genotypes (P < 0.0001). Hepcidin levels were highest among patients with mixed HC/reticuloendothelial system cell (RES) iron deposition. H63D mutations were associated with higher steatosis grades and NAFLD activity scores (odds ratio [OR], ≥1.4; 95% confidence interval [CI]: >1.0, ≤2.5; P ≤ 0.041), compared to WT, but not with either HC or RES iron. NAFLD patients with C282Y mutations had less ballooning or NASH (OR, ≤0.62; 95% CI: >0.39, <0.94; P ≤ 0.024), compared to WT subjects.

Conclusions: The presence of C282Y mutations in patients with NAFLD is associated with greater HC iron deposition and decreased serum hepcidin levels, and there is a positive relationship between hepatic iron stores and serum hepcidin level across all HFE genotypes. These data suggest that body iron stores are the major determinant of hepcidin regulation in NAFLD, regardless of HFE genotype. A potential role for H63D mutations in NAFLD pathogenesis is possible through iron-independent mechanisms.

Figure 1

A) Proportion of subjects with different hepatic iron phenotypes according to their HFE mutation status. The percentage of the total subjects for each HFE genotype or combination of genotypes having stainable hepatic iron in each of the three patterns HC, RES or mixed HC/RES are shown in the pie charts. The percentage of the total is labeled for each pattern. The combined total percentage of subjects having any HC iron (ie., HC only plus HC/RES) are shown in brackets. B) Proportion of subjects with combined C282Y, H63D or WT/WT genotypes according to their hepatic iron phenotypes. The percentage of the total subjects with each iron staining pattern and C282Y/WT plus C282Y/H63D, H63D/WT plus H63D/H63D or WT/WT genotypes are shown in the pie charts. * p<0.05 compared to WT/WT; # p<0.05 compared to subjects without stainable iron.

Figure 2

Mean histological HC and RES iron grade according to HFE genotype. Differences in mean HC iron grade for each HFE genotype compared to WT/WT were determined using ordinal regression modeling after adjustment for other potential contributing factors selected a priori including age at biopsy, sex, BMI, history of GI bleeding or iron overload, dietary or supplemental iron and vitamin C, (OR >2.4, 95% CI >1.4<23.4, # p≤0.001). Standard deviations are indicated by the error bars.

Figure 3

Comparison of the median serum hepcidin values of NAFLD subjects with C282Y and WT HFE genotypes with or without stainable hepatic iron. Significant differences between groups are indicated by arrows (Wilcoxon rank-sum test). Median levels of each group are labeled.

Figure 4

Comparison of the median serum hepcidin values of NAFLD subjects with different hepatic iron phenotypes. There was a significant difference between groups (Kruskal-Wallis test, p<0.0001). Significant post-hoc pairwise comparisons between groups are indicated by arrows (Dunn’s test). Median levels of each group are labeled.